The development of a consistent and long-range investigation of marine natural products and the correlation of the structure of these natural products with biological activity is the continuing goal of this project. The specific aims of the present project are to undertake a systematic biosynthetic study of the novel lipids from the sponges Ectyoplasia ferox, Plakortis halichondroides, and Euryspongia rosea. This study will involve the synthesis and feeding of carefully chosen precursors following the radioactive label throughout the biosynthetic pathway. The problem of endosymbiotic organisms and seasonal variations will also be addressed. Parallel to the above mentioned work, we will isolate and characterize the phospholipids, glycolipids, plasmalogens, and other similar species present in the above mentioned sponges and assess them for biological activity, in particular their neuroactivity since the likelihood exists that unusual membrane phospholipids may modulate neurotransmitter receptors in unique ways. The importance of lipids is noteworthy. Dietary lipid has marked effect on the growth of mammary tumors. High levels of dietary fat have been shown to promote the development of mammary tumors with polyunsaturated fats being found to be more effective than saturated fats. The biological activity of many lipids has also been of interest. There is increasing evidence that certain ether lipids, and their derivatives, represent a new group of drugs that have proven active in the experimental therapy of cancer and leukemia. On the other hand, deficiencies in fatty acid metabolism have been linked to serious health disorders. To develop students (graduate and undergraduate) in the area of marine natural products is another goal of this project.